Abstract

Controlling the surface structure and composition at the atomic level is an effective way to tune the catalytic properties of bimetallic catalysts. Herein, we demonstrate a generalized strategy to synthesize highly monodisperse, surfactant-free octahedral PtxNi1−x nanoparticles with tunable surface structure and composition. With increasing the Ni content in the bulk composition, the degree of concaveness of the octahedral PtxNi1−x nanoparticles increases. We systematically studied the correlation between their surface structure/composition and their observed oxygen reduction activity. Electrochemical studies have shown that all the octahedral PtxNi1−x nanoparticles exhibit enhanced oxygen reduction activity relative to the state-of-the-art commercial Pt/C catalyst. More importantly, we find that the surface structure and composition of the octahedral PtxNi1−x nanoparticles have significant effect on their oxygen reduction activity. Among the studied PtxNi1−x nanoparticles, the octahedral Pt1Ni1 nanoparticles with slight concaveness in its (111) facet show the highest activity. At 0.90 V vs. RHE, the Pt mass and specific activity of the octahedral Pt1Ni1 nanoparticles are 7.0 and 7.5-fold higher than that of commercial Pt/C catalyst, respectively. The present work not only provides a generalized strategy to synthesize highly monodisperse, surfactant-free octahedral PtxNi1−x nanoparticles with tunable surface structure and composition, but also provides insights to the structure-activity correlation.

Keywords

PtNi octahedral concave surface structure oxygen reduction reaction

Yizhong Lu received his PhD from Changchun Institute of Applied Chemistry in 2015. He then joined Prof. Xin Wang’s group as a research fellow at Nanyang Technological University & Cambridge Center for Advanced Research in Energy Efficiency in Singapore. Currently, he is a professor in the School of Material Science and Engineering, University of Jinan, Shandong. His research interests focus on the design and synthesis of electrocatalysts for fuel cells.

Xin Wang received his PhD degree in chemical engineering from Hong Kong University of Science and Technology in 2002. He joined Nanyang Technological University as an assistant professor in 2005 and was promoted to associate professor with tenure in 2010 and full professor in 2016. His research is focused on electrocatalysis and electrochemical technology for energy harvesting. He is currently a Fellow of Royal Society of Chemistry (FRSC).

Notes

Acknowledgments

This research was supported by the National Research Foundation, PrimeMinister’s Office, Singapore under its CREATE Programme. We also acknowledge financial support by the Defence Acquisition Program Administration and Agency for Defence Development (UD120080GD), Republic of Korea.